AUGUSTA — Central Maine Power Co. plans a major project to clean up and contain coal tar left next to, and likely underneath, Bond Brook at the site of the former Augusta Gas Works.

Coal tar is a potentially cancer-causing toxic substance created as a byproduct of the once-commonplace gasification process. Coal was converted into gas to provide heat and light lamps and streetlights from the 1800s through the 1950s.

The former Augusta Gas Works, roughly at the site of what is now Rockingham Electric between Bond Brook and Mount Vernon Avenue, operated from 1853 to the 1950s, according to John Carroll, a spokesman for Central Maine Power Co.

“They were in every major town,” Carroll said of gasification plants. “We’ve done one or two of these a year, for the past 10 years, in different towns. It was the fuel of choice for decades. The way it was structured, processed and disposed of was common practice 100 years ago.”

Carroll said the project, estimated to cost between $1.5 million and $2 million, will take place this summer between June and September, to minimize the impact on fish habitat. Bond Brook is spawning grounds to the endangered Atlantic salmon.

Because the project will require fill materials to be placed on the bottom of Bond Brook, a U.S. Army Corps of Engineers permit is also required.

CMP bought the site and functioning plant in 1911 from Kennebec Light and Heat Co., then sold it in 1949, when it became the Augusta Gas Company.

The plant stored the byproduct coal tar in deep tanks beside Bond Brook, which itself runs through a deep ravine in the area.

And remnants of the toxic substance remain in soils under the site.

Because of the difficulty of removing the contaminated soil in such a steep, confined area, CMP, with the state Department of Environmental Protection’s approval, plans to remove what it can but leave the rest behind and contained.

The project will put in a barrier material under the ground and water to absorb the remaining coal tar and prevent it from seeping to the surface of the ground, or into the waters of Bond Brook.

“The plan is to remove some, and cover the remaining coal tar, so it’s inaccessible, and monitor it to make sure it stays inaccessible,” said Brian Beneski, project manager for DEP. “The biggest threat with this material is through contact. You want to limit access to it. That’s the goal of remediation — to remove any accessibility to the coal tar.”

Beneski advised people, including nearby residents, to stay away from the site of the pollution. While the steeply banked spot doesn’t see much use anyway, it is even more off-limits now due to a major, ongoing Greater Augusta Utility District sewer line replacement project, which skirts around the former Augusta Gas Works site.

Carroll said CMP has cleaned up coal tar at several former gas plant sites across the state during the last several years. He said officials have been aware of likely coal tar contamination at the Augusta site for years.

Beneski said one reason the project was held off until now was to wait for the Greater Augusta Utility District project to come through the area.

It’s “so we could be as efficient as possible, and make sure we’re not ripping up each other’s work,” he said.

CMP is doing the work with some oversight by DEP through the Voluntary Response Action Program, which is intended to encourage the cleanup and redevelopment of contaminated properties.

In the program, participating companies voluntarily clean up polluted sites, with consultation from the DEP. If the work is done to the department’s satisfaction, the company involved receives a certificate of completion indicating it will not be subject to DEP enforcement actions involving the known contaminants.

However, that program does not protect the company from third-party actions, or provide protection from liability for other, unknown pollution on the site.

Carroll said CMP is taking responsibility for the cleanup because the company owned the plant at one time and is the only remaining entity capable of taking responsibility.

“We owned it once, we’re the last ones standing, so we’re the ones to clean it up,” Carroll said. “We want to take responsibility.”

Beneski said the owner of the site, Rockingham Electric, which according to city assessing records has owned the property since 1986, bears no responsibility other than allowing access so the cleanup can take place.

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